Questions about fire rendering

Practical and theoretical implementation discussion.
Post Reply
shiqiu1105
Posts: 138
Joined: Sun May 27, 2012 4:42 pm

Questions about fire rendering

Post by shiqiu1105 » Sun Apr 07, 2013 3:39 am

I am very interesting in fire rendering.

However, most of the papers I found on this topic only talks about rendering fire itself.
However, fire emits light and is an obvious light source.

I am wondering I to sample fire as a light source, as it doesn't have a shape like a normal area light in ray tracer.
And, in algorithms such as BDPT, how to determine if ray intersects with the fire.


keldor314
Posts: 10
Joined: Tue Jan 10, 2012 6:56 pm

Re: Questions about fire rendering

Post by keldor314 » Mon Apr 08, 2013 10:44 pm

Basically, you just have to ray march through the fire volume for every light sample, much like you would for primary rays.

shiqiu1105
Posts: 138
Joined: Sun May 27, 2012 4:42 pm

Re: Questions about fire rendering

Post by shiqiu1105 » Tue Apr 09, 2013 2:36 pm

keldor314 wrote:Basically, you just have to ray march through the fire volume for every light sample, much like you would for primary rays.
But to what direction do you fire the sampling ray?

ingenious
Posts: 282
Joined: Mon Nov 28, 2011 11:11 pm
Location: London, UK
Contact:

Re: Questions about fire rendering

Post by ingenious » Tue Apr 09, 2013 4:26 pm

shiqiu1105 wrote:But to what direction do you fire the sampling ray?
That's a good question. The easiest way is to just do the most basic path tracing and whenever a ray intersects the volume, you match through it and accumulate the volume emission. This is how I think Arnold has it implemented (judging from their EGSR 2012 paper on volumetric rendering). Alternatively, you can choose random points inside the fire volume and compute explicit direct illumination (and combine the two strategies with MIS of course). It's interesting to derive a good distribution for importance sampling the points in the volume.

Post Reply